H-64 mask

The H-64 was a half-mask cartridge respirator made by Mine Safety Appliances (MSA) and widely issued from the 1960s onward for dust protection, including in asbestos work. It used replaceable filter cartridges and a rubber facepiece and became standard equipment in shipyards, refineries, construction, and insulation trades during peak asbestos use.

Origin

The H-64 designation comes from MSA's internal product numbering system. MSA introduced the mask in the early 1960s as part of its Comfo line of half-mask respirators, marketing it as adequate dust protection in workplaces where asbestos exposure was already known to cause disease.

Significance in Asbestos Context

The H-64 is significant because it was often the only respiratory protection workers received, even though internal industry documents and later litigation revealed that half-mask cartridge respirators of that era did not reliably protect against asbestos fibers, especially without fit testing, proper cartridge selection, or training. Lawsuits against MSA and against employers who relied on the H-64 have argued that the company knew or should have known the mask was inadequate for asbestos and failed to warn workers. If you wore an H-64 or a similar MSA respirator on the job, that fact can both document your exposure (because masks were issued where dust was visible) and support a claim that the protection you were given was insufficient.

Example Sentence

During his deposition, the retired pipefitter recalled being handed an H-64 mask each morning at the shipyard and told it was "good enough" for the asbestos insulation work, even though dust filled the compartments.

Related Terms

Mine Safety Appliances (MSA), respirator, failure to warn, occupational exposure, shipyard exposure, personal protective equipment (PPE)

Notes

• If you remember the brand, model, or appearance of any respirator you were issued, write it down and tell your legal team. Respirator manufacturers like MSA, American Optical, and 3M are named defendants in many asbestos cases.
• Look for old pay stubs, safety training records, union records, or employer-issued equipment lists that may confirm which masks were provided and when.
• Co-workers who used the same mask can be valuable witnesses; note their names and last known contact information while memory is fresh.
• Be specific in medical and legal interviews about whether you were ever fit-tested, trained on cartridge changes, or warned that the mask might not stop asbestos fibers. These details matter to a failure-to-warn claim.